Qualitative Analysis Test for Ions - Merit Tutors · 2018-05-25 · nitrate solution (1) yellow...

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Qualitative Analysis

Test for Ions Mark Scheme 1

Level Edexcel

Subject Chemistry

Exam Board GCSE(9-1)

Topic Separate Chemistry 2

Sub Topic Qualitative Analysis: Test for Ions

Booklet Mark Scheme 1

Time Allowed: 53 minutes

Score: /44

Percentage: /100


Question

Number

Answer Acceptable answers Mark

1(a)(i) A calcium ion, Ca2+ (1)

Question Number


1(a)(ii) A description including

white (1)

precipitate/ppt/ppte/solid (1)

Maximum 1 mark if bubbles / fizzing / effervescence also

mentioned

Ignore colour of solution

Ignore cloudy Ignore off white/milky

Allow crystals (1) Ignore powder

Ignore name of precipitate

(2)

Question

Number


1(b) B lead chloride (1)

Question Number


1(c)(i) (barium chloride (aq) + sodium sulfate (aq) →)

sodium chloride (aq) + barium sulfate (s)

sodium chloride (1)

(sodium chloride) (aq) and

barium sulfate (s)both state symbols matched to the

correct product (1)

Allow NaCl (1)

Do not allow sodium chlorine

Accept BaSO4 for barium

sulfate Accept (aq) if sodium chlorine given

Do not allow (solid) Do not allow (AQ)

(2)


Question

Number


1(c)(ii) An explanation linking

{barium sulfate/it} is

{insoluble / does not dissolve}(1)

so it {cannot enter/cannot mix

with/is not absorbed} into the{blood(stream)/body}

orit passes through the body(unchanged) (1)

{barium sulfate/it} does not

dissolve into the blood(stream) (2)

Allow barium is insoluble / does not

dissolve (1) Ignore barium sulfate is a

precipitate

Ignore it cannot be digested

(2)


Question Number


2(a)(i) C iodide, I- (1)

Question

Number


2(a)(ii) A description linking two points

from

flame test / description of

flame test mentioning inflame (1)

sodium gives a yellow

flame (1)

potassium gives a{lilac/purple/violet} flame(1)

description can be using

(nichrome) wire or damp splint Ignore: hold over/

around/under/above flame

Ignore: yellow-orange, orange or

any other colour

(2)

Question Number


2(b)(i) A description linking

blue (1)

precipitate / solid (1)Marked independently.

If further, incorrect observations given, use list principle

allow appropriate qualifiers: e.g. ‘light blue’ but not other colours

eg green-blue allow ppt

(2)


Question Number


2(b)(ii) Cu2+ + 2OH- → Cu(OH)2 (3)

Identifies Cu2+ on LHS and Cu(OH)2 on RHS in equation format (1)

OH- formula on LHS (1) These two marks are

independent and can be scored even if additional ions, correct or incorrect, are given

balancing correct symbols (1)

This mark is only awarded for a fully correct ionic equation with no additional ions

allow multiples accept Cu2+(OH-)2

allow Cu++/ Cu+2

reject incorrect symbols such as cu2+, Oh- etc.

ignore: state symbols allow = instead of →

(3)


Question Number


3(a)(i) A description linking

add dil nitric acid then silvernitrate solution (1)

yellow precipitate/solid (1)

allow silver nitrate solution alone(1) reject if wrong reagent / acid mentioned

colour and form both required reject cream reject yellow-orange (2)

Question Number


3(a)(ii) A description linking

add to sodium hydroxide(solution) and warm (1)

test gases with (moist ) (red)litmus paper (1)

(litmus paper) turns blue (1)

allow sodium hydroxide (solution) alone (1) allow heat solid alone (1) allow Universal Indicator paper/ pH paper(1) allow correct colour change for named indicator (3)

Question Number


3(a)(iii) C iron(III), Fe3+ (1)


Question Number


3(b) A description to include

white {precipitate/solid}with calcium (ions) (1)

white {precipitate/solid}with aluminium (ions) (1)

(precipitate/solid) dissolvesin excess for aluminium ions/ (precipitate/solid) remainsin excess for calcium ions(1)

3rd mark dependent on first and/or second mark being awarded

both (ions) form a white (1) {precipitate/solid} (1) allow ‘both will turn white’ for 1 mark

allow ‘more’ for ‘excess’ ignore clear

(3)


Question number

Answer Mark

4(a) An explanation that combines identification – understanding (1 mark) and reasoning/justification – understanding (1 mark): • the flame test only confirms the presence of lithium ions/Li+ (1)• but another test is needed to confirm the identity of the

anion/negative ion/CO32− (1)

OR

• the red flame test shows the presence of calcium ions Ca2+ andnot lithium ions/Li+ (1)

• the student did not test for carbonate ions (1) (2)

Question number

Answer Mark

4(b) • name: sodium sulfate (1)• formula: Na2SO4 (1)

Allow formula consequential on incorrect name (2)

Question number

Answer Mark

4(c) C (1)

Question number

Answer Additional guidance Mark

4(d)(i) An answer that provides a description by making reference to: • test gas with moist (red) litmus

paper (1)• turns blue (1)

Allow universal indicator paper/pH paper and yellow to blue/purple

(2)

Question number


4(d)(ii) An answer that provides a description by making reference to: • iron(II) – green/pale green/grey-

green and precipitate /solid (1)• iron(III) – red-brown/brown and

precipitate /solid (1)

Allow two correct colours (1)

(2)

Question number

Answer Mark

4(d)(iii) (Fe3+ + 3OH−) → Fe(OH)3 (1)


Question Number


5(a) C (1)

Question Number


5(b) CuCl2 ensure that 2 is subscript at most half the size of Cl and cases are correct

ignore correct charges reject an overall charge

(1)

Question Number


5(c) D (1)

Question Number


5(d) A description including the following

• put/mix/react (sodium)carbonate and acid in(conical) flask (1)

• put limewater in testtube(1)

• (carbon dioxide produced)turns lime water{milky/cloudy/whiteprecipitate} (1)

2 max if reactants and limewater are in the wrong vessels with the correct test

marks can be awarded for the first two marking points by labelling the diagram

“reactants” for sodium carbonate and acid

(3)


Question Number


5(e) A description including three of the following

• make {solutions/dissolve}/{mix/react} solutions (1)

• precipitate (of coppercarbonate) (1)

• filter (1)

• wash (with water) (1)

• leave to dry/dry inoven/dry between filterpaper (1)

max 2 marks if clear error in process, e.g. heat/add acid/evaporate

ignore colours of precipitate accepts forms a solid for precipitate

(3)




Level Edexcel

Subject Chemistry






Score: /45

Percentage: /100


Question Number


1(a) C : copper sulfate and sodium chloride

(1)

Question Number


1(b) copper sulfate (1) blue-green (1)

or

sodium chloride (1) yellow (1)

colour mark consequential on correct metal (compound)

allow blue or green or green-blue

reject orange and yellow-orange

(2)

Question Number


1(c)(i) An explanation linking

weak intermolecular forces /weak forces between molecules (1)

little {heat / energy} needed to separate (molecules) (1)

bonds / attractions in place of forces

intermolecular forces between {atoms / bonds} loses 1st marking point

any answer in terms of covalent or ionic bonding scores zero

(2)

Question Number


1(c)(ii) A description linking

use separating funnel (1)

run off lower {layer / liquid} / OWTTE (1)

alternative description of separating funnel eg funnel with a tap at the bottom suitable labelled diagram burette

allow layers / liquids to separate

ignore fractional distillation

(2)


Question Number


1(d)

shared pair in molecule (1) rest of molecule consequent on first mark (1)

Allow a diagram without labels for 2 marks

any symbols shown must be correct for the 2nd mark

allow any combination of dots and crosses for electrons

wrong compound = zero marks

(2)


Question Number

Answer Mark

2(a)

symbol number of electrons

atom ion atom ionchlorine 18sodium Na+ 11 (3)

Question Number


2(b)(i) NaCl + AgNO3 → NaNO3 + AgCl

• reactant formulae (1)

• product formulae (1)

Ag+ + Cl- → AgCl

ignore state symbols

do not give (2) if incorrectly balanced (2)

Question Number

Answer Acceptable answers

Mark

2(b)(ii) to remove other ions that would also form a white precipitate

(1)


Question Number

Indicative content Mark

QWC *2(c) An explanation linking some of the following points

For a sample to conduct electricity

• charged particles must be present• they must be free to move

water does not conduct because it • is (simple molecular) covalent• exists as molecules• contains no/(very few) charged particles

solid sodium chloride does not conduct because • although it contains ions / cations / anions• which are charged particles• they are not free to move• because they are held together• by strong• electrostatic forces/ ionic bonds• in lattice

sodium chloride solution conducts because • ions / cations / anions are present• which are charged particles• they are free to move• because the water has cut down the forces between the ions• ions have separated• move to electrode of opposite charge (6)

Level 0 No rewardable content 1-11 • a limited explanation e.g. water is covalent and sodium chloride is

ionic • the answer communicates ideas using simple language and uses

limited scientific terminology • spelling, puncuation and grammar are used with limited accuracy

3-22 • a simple explanation e.g. water is covalent and does not conductbecause there are no charged particles: sodium chloride is ionic therefore solution conducts because ions move

• the answer communicates ideas showing some evidence of clarityand organisation and uses scientific terminology appropriately

• spelling, puncuation and grammar are used with some accuracy33 5- • a detailed explanation e.g. in solid sodium chloride the ions are held

in a lattice by strong forces but in sodium chloride solution the ions are free to move: water is covalent so contains no charged particles

• the answer communicates ideas clearly and coherently uses a rangeof scientific terminology accurately

• spelling, puncuation and grammar are used with few errors


Question Number


3(a)(i) B lead chloride (1)

Question Number


3(a)(ii) An explanation linking two of

• strong (electrostatic) forces ofattraction

• between oppositely chargedions

• so requires lot of heat/energyto overcome forces/breakbonds

Any reference to molecules/molecular/intermolecular/covalent scores 0 marks

strong (ionic) bonds

positive and negative ions reject charged atoms for this mark

ignore hard to melt/high temperature needed (2)

Question Number


3(a)(iii) A description including

• M1 add (dilute) nitric acid

• M2 add silver nitrate(solution)

• M3 forms white ppt/solid

Accept correct formulae

If use any other acid can score M2 and M3

dependent on use of silver nitrate

Alternative method:

Electrolyse (1)

Chlorine formed (1)

Bleaches litmus/pH paper (1) Ignore smell (3)


Question Number

Indicative Content Mark

QWCQWC3(b)

A description including some of the following points

ion formation

• magnesium atoms lose electrons• each magnesium atom loses two electrons• to acquire full outer shell• magnesium (configuration) becomes 2.8• forms Mg2+ ion• electrons transferred to oxygen atoms• oxygen atoms gain electrons• each oxygen atom gains two electrons• oxygen (configuration) becomes 2.8• to acquire full outer shell• forms O2- ion

structure

• magnesium ions attract oxide ions• due to opposite charges• ions pack close together• ratio of ions 1: 1• ions arranged in lattice• giant (ionic) (structure)

diagram can be credited for any points (6)

0 Level No rewardable content 1 1 - 2 • a limited description e.g. magnesium atoms lose electrons and

oxygen atoms gain electrons e.g. magnesium oxide is a giantstructure

• the answer communicates ideas using simple language and useslimited scientific terminology

• spelling, punctuation and grammar are used with limited accuracy2 3 - 4 • a simple description e.g. magnesium atoms lose two electrons to

form positive ions and oxygen atoms gain two electrons to formnegative ions

• e.g. magnesium atoms lose electrons and oxygen atoms gainelectrons and magnesium oxide is a giant structure


• spelling, punctuation and grammar are used with some accuracy3 5 - 6 • a detailed description e.g. each magnesium atom transfers two

electrons to an oxygen atom and the opposite charged ions(Mg2+ /O 2-) formed attract each other to form a giant (ionic) lattice

• the answer communicates ideas clearly and coherently uses arange of scientific terminology accurately

• spelling, punctuation and grammar are used with few errors


Question Number


4(a)(i) A carbonate ion CO32- (1)

Question Number


4(a)(ii) A description including

warm / heat / boil (1)

{gas/ammonia} turns (damp red/pink) litmus blue / (damp red/pink) litmus turns blue when held above (the mixture)(1)

maximum (1) if additional reagents added

ignore any ppt

allow pungent smell / smell of {ammonia/wet nappies} /alkaline gas / effect of ammonia on other named indicators /dense white fumes with conc hydrochloric acid

ignore litmus turns blue in ammonium ions/sodium hydroxide/mixture

do not allow gas/ammonia if blue litmus turns red/pink

(2)

Question Number


4(b) Al3+ + 3OH- → Al(OH)3

OH- (1)

Al(OH)3 (1)

balancing 3, conditional on correct formulae (1)

allow multiples

allow HO- (1)

allow Al(HO)3 (1) do not allow Al(HO)3/lower case h

ignore state symbols/3Na+ on both sides

(3)


Question Number


QWCQWC *4(c) An explanation including some of the following points

test for cation • flame test• if the flame is yellow/not lilac, sodium ions are present• if the flame is lilac/not yellow, potassium ions are

present

test for iodide ions

OR

• make a solution of the crystals in water• add dilute nitric acid• add silver nitrate solution• if there is a yellow precipitate, iodide ions are present• if there is no precipitate, sulfate ions are present• Ag+ + I¯ → AgI

• make a solution of the crystals in water• add chlorine water• then cyclohexane• if the cyclohexane/top layer turns purple, iodide ions

were present• if there is no colour change, sulfate ions are present• Cl2 + 2I- → 2Cl- + I2

test for sulfate ions • make a solution of the crystals in water• add dilute {hydrochloric/nitric} acid• add barium {chloride/nitrate} solution• if there is a white precipitate, sulfate ions are present• if there is no precipitate, iodide ions are present• Ba2+ + SO4

2- → BaSO4

(6)

Level 0 No rewardable content 1 1 - 2 • a limited description of test for any 1 ion e.g. flame test, yellow

flame, sodium ions are present.• the answer communicates ideas using simple language and uses

limited scientific terminology• spelling, punctuation and grammar are used with limited

accuracy2 3 - 4 • a simple description to identify a cation and an anion e.g. if the

substance is sodium sulfate, it will give a yellow flame in a flametest and a white precipitate with barium chloride solution.


• spelling, punctuation and grammar are used with some accuracy3 5 - 6 • a detailed description to identify at least 3 ions e.g. carry out a

flame test, yellow flame, sodium ions present, lilac flame,potassium ions present, add silver nitrate solution to solution ofsubstance, yellow precipitate, iodide ion.

• the answer communicates ideas clearly and coherently uses arange of scientific terminology accurately

• spelling, punctuation and grammar are used with few errors




Level Edexcel

Subject Chemistry






Score: /12

Percentage: /100


Question Number


1(a) (=111)

(= 0.1)

(=0.2)

CaCl2 = 40 + 35.5 + 35.5 (1)

THEN moles = 11.1 / 111

(1) conc = moles x 1000/500 (1)

OR

(=22.2)

(= 0.2)

mass conc = 11.1 x 1000/500 (1) conc = mass conc/111

(1)

0.2 scores 3

ecf: 11.1 / Mr

ecf: mass conc / 111

(3)

Question

Number


1(b)(i) A description linking

pipette (1) one practical point eg draw

liquid up to line/ usepipette filler/ rinse first /read at eye level (1)

ignore burette etc for 1st mpt if using measuring cylinder/

burette allow suitable practical point eg read at eye level/ add dropwise from burette near 25

cm3 (1) ignore as 2nd point: transfer

liquid to flask / safety precautions

(2)

Question

Number


1(b)(ii) D 25.20 cm3 (1)


Question

Number


QWC *1(c) A description / explanation including some of the following points

soft

add soap (solution) shake/ mix lather (immediately)

no scum/ no precipitate

permanent hard add soap (solution) shake

no lather / less than with soft water scum/ precipitate

boiled sample same results / boiling does not change becomes soft after ion exchange but not after boiling

temporary hard

add soap (solution) shake no lather / less than with soft water

scum/ precipitate boiled sample

after boiling precipitate / (lime)scale formed lather (immediately)

credit quantitative approaches e.g. titration with soap solution

(6)


Level 0 No rewardable content

1 1 - 2 a limited description e.g. test and one result / when shaken withsoap, soft water makes lather but no scum

the answer communicates ideas using simple language and useslimited scientific terminology

spelling, punctuation and grammar are used with limited accuracy

2 3 - 4 a simple description e.g. describe test and results to distinguishthe soft water and the two samples that are hard water / when

shaken with a small amount of soap, soft water makes a latherand no scum but the other waters make scum but no (less) lather

the answer communicates ideas showing some evidence of clarityand organisation and uses scientific terminology appropriately

spelling, punctuation and grammar are used with some accuracy

3 5 - 6 a detailed description e.g. describe test and results to identify all

three of the samples / as 3-4 and boil the two hard water samplesand repeat test. That which now gives a lather is temporarily hard

the answer communicates ideas clearly and coherently uses a

range of scientific terminology accurately spelling, punctuation and grammar are used with few errors


Hydrocarbons Mark Scheme 1

Level Edexcel

Subject Chemistry



Sub Topic Hydrocarbons



Score: /49

Percentage: /100


Question Number


1(a)(i) An explanation linking

(a compound containing)

hydrogen and carbon (1)

(hydrogen and carbon) only(1)

contains double / multiple

bond (between carbon atoms)(1)

ignore H and C

reject {ions/molecule} of carbon and hydrogen

reject mixture reject oxygen

ignore ‘spare bonds’

allow carbon atoms not joined to the maximum number of other atoms

(3)

Question Number


1(a)(ii) B cracking (1)

Question

Number


1(a)(iii) A description to include

(bromine water is) orange (1)

decolourises / turns colourless

(1)

allow brown / yellow or combinations eg orange-yellow

ignore red (alone) ignore clear / changes colour /

discolour

(2)


Question Number


1(b)(i) D (1)

Question

Number


1(b)(ii) waterproof / rot-proof / strong /

flexible / does not react with oxygen / water resistant / weather proof

allow durable / tough

ignore ductile / stretchy

(1)

Question Number


1(b)(iii) not biodegradable / persist in landfill sites / does not decompose

ignore answers in terms of burning / allow takes a long time to rot /

decompose / takes up space in landfill

(1)


Question Number

Answer Mark

2(a)

any 3 carbon molecule and one C=C (1) fully correct molecule with all bonds (2)

(2)

Question

Number


2(b)(i) A 333 dm3 (1)

Question Number


2(b)(ii) An explanation linking all / three gases present/

nitrogen, hydrogen andammonia (1)

ammonia decomposes/ammonia turns back toreactants/ reaction goes

both ways / reversible (1)

reject ammonium

ignore incomplete reaction assume that “both reactions” refer to forward and backward

reaction allow dynamic equilibrium

(2)

Question

Number


2(b)(iii) An explanation linking

increased / higher {yield /amount of ammonia} (1)

because fewer (gas)molecules/ moles on RHS/

4 mole(cule)s on left and2 on right/ decreased

volume onRHS/equilibrium shifts toRHS/ equilibrium shifts in

forward direction (1)

mark independently

ignore “high yield”

reject answers referring to exothermic or endothermic

ignore any references to rate

(2)


Question Number


2(b)(iv) An explanation to include

rate increased/ time to

reach equilibrium reduced(1)

because gas moleculescloser / more concentrated(1)

so increased collision rate/ more collisions in a

given time / more frequentcollisions(1)

mark independently

ignore any refs to equilibrium

ignore ‘time is faster’/ allow ‘quicker’

allow atoms/ particles instead of molecules; allow more molecules

present (in same container) do not allow ‘more collisions’

(3)


Question Number


3(a)(i) A explanation linking the following

contains carbon (atoms)and hydrogen (atoms) (1)

only (1)

all single bonds/no doublebonds (1)

reject carbon molecules and hydrogen molecules

ignore no spare bonds (3)

Question Number


3(a)(ii) remains orange (1)

Question Number


3(b)(i) cracking (1)

Question Number


3(b)(ii) any two reasons from

insufficient petrol / supply (from crude oil) (1)

higher demand for petrol (1)

more fuel oil fraction than needed (1)

petrol is more useful than fuel oil (1)

not enough petrol

too much fuel oil

(2)

Question Number


3(c) CH4 + 2O2 CO2 + 2H2O (3)

LHS (1) RHS (1) balancing correct formula (1)

correct multiples ignore state symbols

(3)


Question Number


(4(a) the liquid oil is changed into a solid

(1)

Question Number


4(b)(i) B sodium hydroxide (1)

Question Number


4(b)(ii) An explanation linking any two of

tail / {hydrophobic /hydrocarbon } end into grease(1)head / {anion / hydrophilic}end into water (1)

allows grease to mix withwater when surrounded bysoap (anions) / grease issurrounded by soap (1)

surface tension lowered (1)

allow correctly labelled diagram (2)

head is soluble in water (1)

(2)

Question Number


4(c)(i) propanoic (acid) (1)

Question Number


4(c)(ii) CH3COOH + C2H5OH CH3COOC2H5 (1) + H2O (1) award one mark if incorrectly balanced

correct products but no / incorrect reactants shown (1) allow correct molecular formulae allow correct multiples ignore state symbols

(2)

Question Number


4(d) (making) fibres/fleece/clothing/ fabrics/bedding/computer mouse mats/yarns/ropes/safety belts/filters/insulating tape/wood finishes/(plastic) carrier bags

allow any named item of clothing

(1)


Question Number


5(a) C – CH3CH3

Question Number


5(b) carbon skeleton correct including double bond (1)

rest of molecule correct (1)

allow CH3

(2)

Question Number


5(c) CH4 + 2O2 → CO2 + 2H2O • reactant formulae (1)••

product formulae (1)balancing of correctformulae (1)

accept multiples

reject incorrect use of cases and non-subscripts

(3)


Question Number


QWCQWC *5(d) advantages • renewable / sustainable• more plants can be grown• crops use up carbon dioxide and produce oxygen

when growing /photosynthesising• carbon neutral because the carbon produced during

combustion is used when growing the plants• does not use up crude oil/non-renewable resources

disadvantages • crops grown for bio-fuels use up land• land could otherwise be used to provide homes / less

farmland available for growing food crops• lots of crops required to provide a small amount of

bio-methane• bad season reduces availability• carbon emissions due to transport and production if

qualified

(6)

Level

0 No rewardable content

11 1- • a limited description e.g. using bio-methane conserves fossilfuels and uses up carbon dioxide when plants are grown

• the answer communicates ideas using simple language anduses limited scientific terminology

• spelling, puncuation and grammar are used with limitedaccuracy

22 3- • a simple description e.g. growing plants to produce bio-methane is sustainable and conserves fossil fuels but uses uplots of farm land which could be used to grow plants for food

• the answer communicates ideas showing some evidence ofclarity and organisation and uses scientific terminologyappropriately

• spelling, puncuation and grammar are used with someaccuracy

3 5 - 6 • detailed description e.g growing plants remove carbondioxide from the air during photosynthesis and conservesfossil fuels but lots of crops are required to make bio-methane and this uses up farm land which could otherwisebe used to grow crops for food

• the answer communicates ideas clearly and coherently usesa range of scientific terminology accurately

• spelling, puncuation and grammar are used with few errors



Level Edexcel

Subject Chemistry






Score: /50

Percentage: /100


Question Number


1(a)(i) D C4H10 (1)

Question Number


1(a)(ii)

one C=C in a molecule with three consecutive carbon atoms (1)

rest of structure correct, ignore bond angles, conditional on first marking point(1)

allow -CH3

do not allow two C=C in a molecule

allow (1) for completely correct dot and cross diagram

(2)

Question Number


1(b) C oxidised (1)

Question Number


1(c)(i) A description including two from

• effervescence / fizzing /bubbles of gas (1)

• solid {disappears/clears}/(colourless)solution formed(1)

ignore {cloudy/white ppt} /‘gas formed’/colour change /name of gas / changes to a liquid

(solid/sodium carbonate/it) dissolves (1) (2)

Question Number


1(c)(ii) CH3COOC2H5/CH3COOCH2CH3 / CH3CO2C2H5 / CH3CO2CH2CH3 / C2H5O2CCH3 / CH3CH2OOCCH3 (1)

H2O (1)

allow displayed formulae/ C4H8O2 do not allow formulae ending in –COOH/-COO or any formula that does not show an ester

do not allow H2O / H2O /lower case h/HOH

maximum (1) if additional incorrect balancing ignore state symbols

(2)


Question Number


2(a)(i) LPG, petrol and diesel (1)

Question Number


2(a)(ii) An explanation linking two of the following points

• use of {fractions / large molecules /long chain hydrocarbons} of {lessdemand / less useful / lower value}/ ORA (1)

• to meet demand / small moleculesneeded (1)

reject useless use up excess kerosene / fuel oil and bitumen

to make more petrol / LPG / alkenes

(2)

Question Number


2(b) B the boiling point of the hydrocarbon increases

(1)

Question Number


2(c)(i) C2H4 (1)

Question Number


2(c)(ii)

n

(2) ignore n missing on polymer structure

LHS (1) RHS (1)

Allow:

n

(1) (where X could be CH3 or similar)

n C2H4 → (C2H4)n (2)

Note: Displayed formulae alkene with C=C polymer – single bonds between atoms with continuation bonds

Allow any number of C2H4 on LHS drawn out with corresponding structure of polymer on RHS

(2)


Question Number


2(d)(ii) An explanation linking two of the following points

• sulfur dioxide formed (duringcombustion of fuel) (1)

• sulfur dioxide {dissolves in rain /forms acid (rain)} (1)

• an effect of acid rain e.g. harms{fish / plants / statues / buildings} /lowers pH of lakes (1)

SO2

possible harm to human respiration

(2)

Question Number


2(d)(i) An explanation linking the following points

• greenhouse gas / traps heat inatmosphere (1)

• may lead to increasing globaltemperature / global warming (1)

traps infra-red radiation / increases greenhouse effect

reject reference to UV

melting {ice caps / glaciers} / climate change / sea-level rising / loss of habitats

reject reference to ozone layer (2)


Question number

Answer Mark

3(a) C (1)

Question number


3(b) • molecular formula – C5H10 (1)• structure (1)

(2)

Question number


3(c)(i) •

•

calculates relative molecular mass ofC4H9OH (1)calculates mass of C4H9OH produced(1)

• final answer = 1.9  (kg) (1)

Example of calculation

Relative molecular mass of C4H9OH = (4 × 12) + (9 × 1) + 16 + 1 = 74

Mass of C4H9OH produced = (74 ÷ 56) × 1.4

Accept 1.85  (kg)

Award full marks for use of moles/correct numerical answer without working (3)

Question number

Answer Mark

3(c)(ii) A (1)

Question number

Answer Mark

3(d) • X and Y are both unsaturated/contain {multiple/double}bonds/alkenes (1)

• Z is saturated/contains no {multiple/double} bonds/alkane (1) (2)


Question Number


4(b) • correct repeating unit(1)

• two correct units shown withcontinuation bonds (1)

any answer with double bonds = 0

Allow if correct and more than two units shown (2)

Question Number


4(c) A description including two of the following points

• bromine (water) (1)

• (bromine water) turns (fromorange) to colourless/or isdecolourised (1)

Ignore clear/discoloured (2)

Question Number


4(d)(i) 17 (g) seventeen (g) (1)

Question Number


4(d)(ii) An explanation linking two of the following

• break down of hydrocarbons /large molecules / alkanes (1)

• into small(er) molecules (1)

• into alkanes and alkenes (1)

Reject ‘chains of molecules’ /polymers Ignore chains

(2)

Question Number


4(a) C (1)


Question Number


4(d)(iii) An explanation linking two of the following:

• less demand for (fractionscontaining) large molecules ORA(1)

• large molecules are less usefulORA (1)

• specific use of product fractionse.g. petrol / fuel for cars(1)

• to make alkenes (1)

• specific use of alkenes producede.g. as monomers / to makepolymers / to make plastics (1)

Reject are useless

named alkenes

(2)


Question Number


5(a)(i)

one C=C in a three consecutive carbon atom molecule (1)


allow methyl group written as CH3

(2)

Question Number


5(a)(ii) C7H16 (1)

Question Number


5(b) A description including

add bromine (water) / aqueous bromine (and shake the tube)(1)

stays orange / no change / does not go colourless in {propane/alkane} (1)

turns colourless / decolorises in {propene/alkene} (1)

Maximum 1 mark for 2 correct observations with an incorrect reagent or no reagent specified

Allow recognisable spelling for bromine

Allow yellow / brown or combinations of these for orange

Ignore just ‘red’

Ignore clear / discoloured

one correct test with statement or clear implication that the other must be the other gas for full marks eg add bromine water to both gases, the one that turns it colourless is propene, scores 3 marks as it is clearly implied that the other gas does not turn it colourless

(3)


Question Number


QWCQWC *5(c) An explanation including some of the following points Making the polymer many propene molecules join/react together form a long chain polymerisation reaction propene is the monomer propene is unsaturated / has a double bond poly(propene) has single bonds propene is a gas and forms poly(propene) which is a solid the C=C bond breaks / opens up

Properties of poly(propene) with related uses e.e.property – flexible, low density (lightweight), shatterproof, highsoftening point, non-toxic, strong, tough, good insulator, waterproof, resistant to corrosion, long lasting, can be moulded intoshape, can be made into fibresUses of poly(propene)use – to make plastic bags, packaging, buckets, bowls, foodcontainers, ropes, carpets, thermal underwear, Thinsulateitems, toys, bottles, bottle caps, laboratory equipment, medicalequipment, pipes, car bumpers, crates, furniture, tubing

(6)

0 Level No rewardable content 1 1 - 2 a limited explanation of how to make the polymer or properties or uses

e.g. propene molecules join together to form the polymer / polypropenecan be used to make carpetsthe answer communicates ideas using simple language and uses limitedscientific terminologyspelling, punctuation and grammar are used with limited accuracy

2 3 - 4 a simple explanation of how to make the polymer and/or properties and/or uses e.g. propene molecules are monomers and join together to make poly(propene)/ poly(propene) is used to make buckets because it can be moulded into shape the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, punctuation and grammar are used with some accuracy

3 5 - 6 a detailed explanation including reference to how to make the polymer, its uses and properties e.g. propene molecules have a double bond and poly(propene) can be used to make washing up bowls because it is strong. / propene molecules have a double bond and many of them join together to make polypropene which is used to make ropes. the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors



Level Edexcel

Subject Chemistry






Score: /25

Percentage: /100


Question Number


1(a) remove delivery tube from water before stopping heating

other words which make sequence clear

use of (Bunsen) valve

(1)

Question Number


1(b) C4B H8 (1)

Question Number


1(c) contains a {double/multiple} bond

ignore “spare bonds”

ignore reference to number of hydrogen atoms attached.

(1)

Question Number


1(d) A description to include

• bromine water is orange(1)

• propane: (remains) orange/ no colour change (1)

• propene: becomescolourless /decolourises(1)

red / yellow / brown any combination of these

ignore clear /discolours

(3)


Question Number


1(e) An explanation linking any two of

• shorter chain molecules aremore useful ORA (1)

• demand for shorter chainmolecules ORA (1)

• meets demand

• reduces the excess of longerchain molecules (1)

• (cracking) produces alkenes(1)

• alkenes used to makepolymers (1)

reject long chain molecules are useless

named fraction/use/fuel

named fraction /use/fuel

(2)


Question number

Answer Mark

2(a) C (1)

Question number

Answer Mark

2(b)(i) (oil well) C (1)

Question number

Answer Mark

2(b)(ii) (oil well) A

(1)

Question number


2(c)(i) An explanation that combines identification – application of knowledge (1 mark) and reasoning/justification – application of understanding (2 marks): • when the decane is heated it

vaporises/turns to a gas (1)• decane vapour/gas breaks down as it

comes in contact with hot porous pot(1)

• large molecules of decane producesmaller molecules, including ethene(1)

Do not allow this point if ethane passes over hot porous pot

(3)

Question number

Answer Mark

2(c)(ii) B (1)

Question number

Answer Mark

2(c)(iii) 2C10H22 + 31O2 → 20CO2 + 22H2O

• LHS (1)• RHS both numbers correct (1) (2)


Question Number


3(a) C (1)

Question Number


3(b)(i) An explanation linking two of the following points

• break down of(hydrocarbons/molecules/ alkanes) (1)

• into smaller(hydrocarbons/molecules/ alkanes) (1)

Ignore ‘chains of …..’/ polymers Ignore ‘separating Ignore reasons for cracking

(2)

Question Number


3(b) (ii) an explanation linking the following

• (molecule) containing(carbon-carbon) double /multiple bond (1)

• contains (atoms of)carbon and hydrogen (1)

• only (1)

Allow references to addition reactions. Ignore ‘alkene’, ‘spare bonds’, ‘doesn’t have max no of atoms or H bonded’

Can only score third point if second point scored (3)

Question Number


3(b)(iii) a description including the following

• fromorange/brown/yellow (1)

• to colourless (1)

Allow red-brown but no other mention of red

Ignore clear / discolour (2)


Polymers Mark Scheme

Level Edexcel

Subject Chemistry



Sub Topic Polymers

Booklet Mark Scheme


Score: /51

Percentage: /100


Question number

Answer Mark

1(a) An explanation that combines identification – improvement of the experimental procedure (1 mark) and justification/reasoning which must be linked to the improvement (1 mark): • reverse the boiling tubes/pass gas through the tube in ice water

first (1)• so that if any liquid condenses in the tube it must have come

from the burning wax (and not from the limewater) (1) (2)


Question number


*1(b) Answers will be credited according to candidate's deployment of knowledge and understanding of the material in relation to the qualities and skills outlined in the generic mark scheme.

The indicative content below is not prescriptive and candidates are not required to include all the material which is indicated as relevant. Additional content included in the response must be scientific and relevant.

Candidates choose appropriate monomers to illustrate the formation of different polymers.

• polymer molecules are long chains• made up of simple repeating units

• use chloroethene (only)• to form poly(chloroethene)• which is addition polymerisation• use ethane-1,2-diol and ethanedioic acid• to form a polyester• which is condensation polymerisation

• one of the bonds in the double bond in chloroethene moleculebreaks

• and chloroethene molecules join together to form a long chainmolecule

• equation

• identification of repeat unit

• alcohol group combines with a carboxylic acid group• and an ester (link) formed• with a water (molecule) eliminated• equation

• ester link shown• identification of repeat unit (6)


Level Mark Descriptor

0 No awardable content. Level 1 1–2 • The explanation attempts to link and apply knowledge and

understanding of scientific ideas, flawed or simplistic connectionsmade between elements in the context of the question. (AO2)

• Lines of reasoning are unsupported or unclear. (AO2)Level 2 3–4 • The explanation is mostly supported through linkage and

application of knowledge and understanding of scientific ideas,some logical connections made between elements in the context ofthe question. (AO2)

• Lines of reasoning mostly supported through the application ofrelevant evidence. (AO2)

Level 3 5–6 • The explanation is supported throughout by linkage andapplication of knowledge and understanding of scientific ideas,logical connections made between elements in the context of thequestion. (AO2)

• Lines of reasoning are supported by sustained application ofrelevant evidence. (AO2)

Question number Answer Marks

1(c)(i) carboxylic acids (1)


1(c)(ii)

(1) (1) (2)


Question Number


2(a) C alkenes are unsaturated hydrocarbons

(1)

Question Number


2(b) poly(ethene) (1)

C

H

H

C

H

CH3 n

(1)

polythene/polyethylene

continuation bonds need not go through brackets

Allow bond pointing to any part of CH3

(2)

Question Number


2(c) An explanation linking two of

non biodegradable (1)

persist in landfill sites (1)

OR produce gases/fumes when burnt (1) M1 gases may be toxic/harmful (1) M2

OR cannot be recycled (1)

new {raw material/crude oil} needed (1)

{do not/take (very) long time to} decompose/rot/disintegrate/degrade

stays for long time take up a lot of space (in landfill sites)

a named gas linked to the environmental problem it causes e.g. carbon dioxide is a greenhouse gas

Ignore pollutants

(need to use) finite resources

(2)


Question Number


QWCQWC *2(d) An explanation including some of the following points A good fuel should Burning considerations

• ignite easily

• burn easily

• release a lot of /sufficient heat energy when itis burnt

Usage considerations

• be safe to use

• be safe/easy to transport

• be {safe/easy/convenient} to store

• be reasonably cheap

Supply considerations

• readily available/good supply

• be renewable/sustainable/not finite

Products considerations• not produce (much) solid/ash when burnt

• not produce much/any smoke

• contain little/no sulfur

• not produce {toxic/harmful} gases/fumes

• carbon neutral

• not produce too much carbon dioxide or othernamed gas such as sulfur dioxide or greenhousegases

(6)

Level 0 No rewardable content

1 1 - 2 • a limited description covering two aspects: e.g. burn easily andsafe to use

OR one aspect covered in more detail e.g. is cheap and easy totransport

the answer communicates ideas using simple language and useslimited scientific terminology, spelling, punctuation and grammarare used with limited accuracy


Question Number


3(a)(i) An explanation linking

(a compound containing)

hydrogen and carbon (1)

(hydrogen and carbon) only(1)

contains double / multiple

bond (between carbon atoms)(1)

ignore H and C

reject {ions/molecule} of carbon and hydrogen

reject mixture reject oxygen

ignore ‘spare bonds’

allow carbon atoms not joined to the maximum number of other atoms

(3)

Question Number


3(a)(ii) B cracking (1)

Question

Number


3(a)(iii) A description to include

(bromine water is) orange (1)

decolourises / turns colourless

(1)

allow brown / yellow or combinations eg orange-yellow

ignore red (alone) ignore clear / changes colour /

discolour

(2)


Question Number


3(b)(i) D (1)

Question

Number


3(b)(ii) waterproof / rot-proof / strong /

flexible / does not react with oxygen / water resistant / weather proof

allow durable / tough

ignore ductile / stretchy

(1)

Question Number


3(b)(iii) not biodegradable / persist in landfill sites / does not decompose

ignore answers in terms of burning / allow takes a long time to rot /

decompose / takes up space in landfill

(1)


Question Number


(4(a) the liquid oil is changed into a solid

(1)

Question Number


4(b)(i) B sodium hydroxide (1)

Question Number


4(b)(ii) An explanation linking any two of

tail / {hydrophobic /hydrocarbon } end into grease(1)head / {anion / hydrophilic}end into water (1)

allows grease to mix withwater when surrounded bysoap (anions) / grease issurrounded by soap (1)

surface tension lowered (1)

allow correctly labelled diagram (2)

head is soluble in water (1)

(2)

Question Number


4(c)(i) propanoic (acid) (1)

Question Number


4(c)(ii) CH3COOH + C2H5OH CH3COOC2H5 (1) + H2O (1) award one mark if incorrectly balanced

correct products but no / incorrect reactants shown (1) allow correct molecular formulae allow correct multiples ignore state symbols

(2)

Question Number


4(d) (making) fibres/fleece/clothing/ fabrics/bedding/computer mouse mats/yarns/ropes/safety belts/filters/insulating tape/wood finishes/(plastic) carrier bags

allow any named item of clothing

(1)


Question Number


5(a)(i)

one C=C in a three consecutive carbon atom molecule (1)


allow methyl group written as CH3

(2)

Question Number


5(a)(ii) C7H16 (1)

Question Number


5(b) A description including

add bromine (water) / aqueous bromine (and shake the tube)(1)

stays orange / no change / does not go colourless in {propane/alkane} (1)

turns colourless / decolorises in {propene/alkene} (1)

Maximum 1 mark for 2 correct observations with an incorrect reagent or no reagent specified

Allow recognisable spelling for bromine

Allow yellow / brown or combinations of these for orange

Ignore just ‘red’

Ignore clear / discoloured

one correct test with statement or clear implication that the other must be the other gas for full marks eg add bromine water to both gases, the one that turns it colourless is propene, scores 3 marks as it is clearly implied that the other gas does not turn it colourless

(3)


Question Number


QWCQWC *5(c) An explanation including some of the following points Making the polymer many propene molecules join/react together form a long chain polymerisation reaction propene is the monomer propene is unsaturated / has a double bond poly(propene) has single bonds propene is a gas and forms poly(propene) which is a solid the C=C bond breaks / opens up

Properties of poly(propene) with related uses e.e.property – flexible, low density (lightweight), shatterproof, highsoftening point, non-toxic, strong, tough, good insulator, waterproof, resistant to corrosion, long lasting, can be moulded intoshape, can be made into fibresUses of poly(propene)use – to make plastic bags, packaging, buckets, bowls, foodcontainers, ropes, carpets, thermal underwear, Thinsulateitems, toys, bottles, bottle caps, laboratory equipment, medicalequipment, pipes, car bumpers, crates, furniture, tubing

(6)

0 Level No rewardable content 1 1 - 2 a limited explanation of how to make the polymer or properties or uses

e.g. propene molecules join together to form the polymer / polypropenecan be used to make carpetsthe answer communicates ideas using simple language and uses limitedscientific terminologyspelling, punctuation and grammar are used with limited accuracy

2 3 - 4 a simple explanation of how to make the polymer and/or properties and/or uses e.g. propene molecules are monomers and join together to make poly(propene)/ poly(propene) is used to make buckets because it can be moulded into shape the answer communicates ideas showing some evidence of clarity and organisation and uses scientific terminology appropriately spelling, punctuation and grammar are used with some accuracy

3 5 - 6 a detailed explanation including reference to how to make the polymer, its uses and properties e.g. propene molecules have a double bond and poly(propene) can be used to make washing up bowls because it is strong. / propene molecules have a double bond and many of them join together to make polypropene which is used to make ropes. the answer communicates ideas clearly and coherently uses a range of scientific terminology accurately spelling, punctuation and grammar are used with few errors


Alcohols & Carboxylic Acids Mark Scheme 1

Level Edexcel

Subject Chemistry



Sub Topic Alcohols & Carboxylic Acids



Score: /44

Percentage: /100


Question Number


1(a)(i) C4H8O2 capital letters; numbers must be subscripts ignore structural formulae such as CH3COOCH2CH3 i.e. must have just C4, H8

and O2 in any order.

(1)

Question Number

Answer Mark

1(a)(ii) ethanol + ethanoic acid → ethyl ethanoate + water (2)

LHS= 1 mark [allow acetic acid]; RHS= 1 mark [allow ethyl acetate] Allow = for arrow. Fully correct formula equation = 2 (part mark not possible with

formulae)

(2)

Question Number


1(a)(iii) no vapour/ little vapour (given off) / it is not a gas / it is a solid

(not vapour) OR small amount/ concentration in

sweets

allow gas for vapour allow ethyl ethanoate is in a

liquid state

(1)

Question Number


1(b)(i) D soap (1)

Question Number


1(b)(ii) A description linking filter / decant off water

(1)

(then) wash/rinse (1)

Can only score second mark if

first marking point awarded

ignore anything before filtering that would not contaminate soap

but do not allow to evaporate water/ heat BEFORE filtering

ignore anything after washing, including drying

(2)

Question Number

Answer Mark

1(c) C unsaturated molecules in the liquid oil become saturated (1)


Question Number


2(a)(i) A description including two of the following

dissolve the sugar/aqueous

solution (1) warm/ 25-40°C (1)

in absence of air / no

oxygen/ anaerobic / attachairlock (1)

pH neutral / slightly acidic/4-7

sterile conditions

ignore any mention of pressure

ignore incorrect answers

ignore heat / hot

allow any temperature or range within 25-40 allowed

ignore clean etc

ignore ‘optimum’ {temp/pressure/pH}

(2)

Question

Number


2(a)(ii) B fractional distillation (1)

Question Number


2(a)(iii) C6H12O6 → 2 C2H5OH + 2 CO2

(2)

correct formulae (with no others) (1)

balancing the three formulae (1) ignore state symbols

allow C2H6O/ CH3CH2OH for C2H5OH

reject CO2 / CO2

allow multiples

(2)

Question

Number


2(b)(i) Any two of

(reacts with) steam (1) catalyst/phosphoric acid (1) high temperature / 200°C

- 4500C (1) high pressure/ 50-100 atm

(1)

allow reacts with water ignore incorrect catalyst ignore hot / heat

(2)


Question Number


2(b)(ii) An explanation linking any three of LAND: country needs land for: farming / food / crops / homes /not enough land to grow

sugar crop for fermentation (1)

OIL SUPPLY: (reliable supply of) crude oil for ethene (1)

SPEED: fermentation slow/batch; hydration continuous/ fast (1)

PURITY: hydration makes {pure(r) ethanol / high concentration} (1)

ATOM ECONOMY: higher atom economy for

ethene process (1)

ignore incorrect responses ignore land needed

for growing yeast

ignore cheaper/

easier

ignore yield

(3)


Question Number


(3(a) add yeast, temperature of 35oC (1)

Question Number


3(b) C2H4 (1) + H2O (1) → C2H5OH

award one mark max if incorrectly balanced

allow correct molecular formula C2H6O allow H4C2correct multiples ignore state symbols (2)

Question Number


3(c)(i) A description linking any two from

same general formula (1) same functional group (1) (consecutive) compounds

differ by CH2 (1) gradual variation in physical

properties (1)

{similar / same} chemical{properties / reactions} (1)

allow CnH2n+1OH (2) allow CnH2n or any correct general formula (2)

ignore same properties/physical properties

allow a correct trend, e.g. bp increases with number of carbon atoms (1)

(2)

Question Number


3(c)(ii) allow –OH allow correct dot and cross diagram

(1)

Question Number


3(d)(i) oxidation (1)


Question Number


3(d)(ii) A description including any two from effervescence/fizzing/bubbling

(1)

solid disappears (1)

colourless solution (1)

ignore incorrectly named gases ignore gas given off/evolved allow magnesium floats on surface of acid

allow solid dissolves (1)

ignore solution turns colourless ignore clear (2)


QQuestion NNumber 4(a)

QQuestion NNumber 4(b)

C2H4 +

A descrfrom

• d/

• (

•r

• a{a

Answer

C H2OO

C2H4 as

rest of eeon C2H4

orrect coas a reac

Answer

issolve sussugar sol

aadd) yeas

wwarm / an

air/oxyge

22H5OH

reactantt (1)

quation cctant (1)

iiption incluu

gar in wauution (1)

tt (1)

yy temperaaange withii

naerobic //n}

pparatus ((} c en1)

nnditional

ding any two

tter

ture or n 15 to 400oC (1)

{no/littlee} ter the

do not allh/HOH

allow C2H

ignore ca

allow rooignore heeat unlesstemperatignore o

do not allignore fr

Acceptabll

ignore staa

Acceptabll

allow gluccrbohydrat

mm temper

ure pptimum te

e answerss

ow H2O /

6O for ethhanol te symbools

e answerss

ose solutiion e

aature specified

ow just ‘saactional disstillation

H2O /loweer case

mmperaturee

ealed conttainer’

Mark

(2)

Mark

(2)


Question Number


4(c) An explanation linking

Marking point 1 – sugar- one from • sugar obtained from {plants

/crops/specific crop} (1)• (plenty of) land available to grow

{plants /crops/specific crop} (forfermentation)(1)

Marking point 2 - ethene • ethene obtained from {crude oil /

fractional distillation /cracking}(1)

Marking point 3 – cost/energy – one from

• cannot afford to buy crude oil (1)• crude oil is too expensive (1)• more expensive to

{use/buy/produce} ethene (1)• cheaper to use fermentation (1)

ignore answers that just repeat the information in the question

ignore vague answers such as carbon neutral/environmentally friendly

for marking point 1 OR 2, allow plants renewable/{crude oil/ethene} non-renewable (1)

allow {little/no} {heat/energy} required for fermentation (1) allow {high temperature /high pressure} required for hydration of ethene (1)

(3)

Question Number


4(d) An explanation including any two from

• formulae differ by CH2

• same general formula

• all have {OH/hydroxyl group}

general formula is CnH2n+1OH (2)

allow increase by {CH2/1 carbon and 2 hydrogens}

do not allow incorrect general formula

allow have similar chemical {reactions /properties}/same functional group/OH from an incorrect general formula

ignore ‘hydroxide’/all end in (an)ol /all alcohols

ignore physical properties

maximum (1) if hydroxide ions /carboxyl group

(2)


Question Number


5(a)(i) D C4H10 (1)

Question Number


5(a)(ii)

one C=C in a molecule with three consecutive carbon atoms (1)


allow -CH3

do not allow two C=C in a molecule

allow (1) for completely correct dot and cross diagram

(2)

Question Number


5(b) C oxidised (1)

Question Number


5(c)(i) A description including two from

• effervescence / fizzing /bubbles of gas (1)

• solid {disappears/clears}/(colourless)solution formed(1)

ignore {cloudy/white ppt} /‘gas formed’/colour change /name of gas / changes to a liquid

(solid/sodium carbonate/it) dissolves (1) (2)

Question Number


5(c)(ii) CH3COOC2H5/CH3COOCH2CH3 / CH3CO2C2H5 / CH3CO2CH2CH3 / C2H5O2CCH3 / CH3CH2OOCCH3 (1)

H2O (1)

allow displayed formulae/ C4H8O2 do not allow formulae ending in –COOH/-COO or any formula that does not show an ester

do not allow H2O / H2O /lower case h/HOH

maximum (1) if additional incorrect balancing ignore state symbols

(2)


Alcohols & Carboxylic Acids Mark Scheme 2

Level Edexcel

Subject Chemistry



Sub Topic Alcohols & Carboxylic Acids



Score: /11

Percentage: /100


Question number

Answer Mark

1(a) An explanation that combines identification – improvement of the experimental procedure (1 mark) and justification/reasoning which must be linked to the improvement (1 mark): • reverse the boiling tubes/pass gas through the tube in ice water

first (1)• so that if any liquid condenses in the tube it must have come

from the burning wax (and not from the limewater) (1) (2)


Question number


*1(b) Answers will be credited according to candidate's deployment of knowledge and understanding of the material in relation to the qualities and skills outlined in the generic mark scheme.

The indicative content below is not prescriptive and candidates are not required to include all the material which is indicated as relevant. Additional content included in the response must be scientific and relevant.

Candidates choose appropriate monomers to illustrate the formation of different polymers.

• polymer molecules are long chains• made up of simple repeating units

• use chloroethene (only)• to form poly(chloroethene)• which is addition polymerisation• use ethane-1,2-diol and ethanedioic acid• to form a polyester• which is condensation polymerisation

• one of the bonds in the double bond in chloroethene moleculebreaks

• and chloroethene molecules join together to form a long chainmolecule

• equation

• identification of repeat unit

• alcohol group combines with a carboxylic acid group• and an ester (link) formed• with a water (molecule) eliminated• equation

• ester link shown• identification of repeat unit (6)


Level Mark Descriptor

0 No awardable content. Level 1 1–2 • The explanation attempts to link and apply knowledge and

understanding of scientific ideas, flawed or simplistic connectionsmade between elements in the context of the question. (AO2)

• Lines of reasoning are unsupported or unclear. (AO2)Level 2 3–4 • The explanation is mostly supported through linkage and

application of knowledge and understanding of scientific ideas,some logical connections made between elements in the context ofthe question. (AO2)

• Lines of reasoning mostly supported through the application ofrelevant evidence. (AO2)

Level 3 5–6 • The explanation is supported throughout by linkage andapplication of knowledge and understanding of scientific ideas,logical connections made between elements in the context of thequestion. (AO2)

• Lines of reasoning are supported by sustained application ofrelevant evidence. (AO2)


1(c)(i) carboxylic acids (1)


1(c)(ii)

(1) (1) (2)


Bulk & Surface

Properties of Matter Mark Scheme

Level Edexcel

Subject Chemistry



Sub Topic Bulk & Surface Properties of Matter (inc Nanoparticles)

Booklet Mark Scheme


Score: /10

Percentage: /100


Question number

Answer Mark

1(a) An explanation that combines identification via a judgement (maximum 2 marks) to reach a conclusion via justification/reasoning, which must be linked to the judgement (maximum 2 marks): • it is lighter/has a lower density/than steel (1)• so it is easier/more comfortable to wear (1)

OR • it is stronger (1)• so it is less likely to be penetrated (1)

OR • it is more flexible (1)• so it is easier/more comfortable to wear (1)

OR • does not (corrode/rust) (1)• so it will last longer (1) (4)

Question number


1(b)(i) • calculates total surface area (1)• calculates volume (1)• calculates surface area to volume

ratio (1)

Example of calculation

Surface area = 6 × 2 × 2 = 24  (cm2) Volume = 2 × 2 × 2 = 8  (cm3) Surface area to volume ratio = 24/8 = 3  :  1

Award full marks for correct numerical answer without working (3)

Question number

Answer Mark

1(b)(ii) An explanation that combines identification – application of knowledge (1 mark) and reasoning/justification – application of understanding (2 marks): • silver nanoparticles have a much greater surface area to volume

ratio than powder (1)OR • silver nanoparticles have a much greater surface area than the

same volume of a powder (1)

Plus • because chemical reactions take place on the surface of the solid

silver catalyst (1)• so there will be more frequent collisions/the rate of reaction will

be faster (1)OR • So in a given time, more molecules can come together to react

(1) (3)

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